1. Field of the Invention
The present invention relates to a wireless communication system, or more in particular to a frequency-hopped wireless communication system comprising a plurality of wireless communication equipment for performing mutual communication while hopping transmission and receiving frequencies in synchronism with a base station, and a mobile wireless terminal.
2. Description of the Related Art
The conventional mutual communication systems comprising a plurality of wireless communication equipments for performing communication with each other are classified into three types including peer decentralization, centralization and hybrid, as seen in the wireless LAN system described in "Illustrated Standard LAN Text (Vol. 2)", pp. 63-96 (Reference 1), by Seiji Uehara, published by ASCII Publication, for example. The "peer decentralization" is the type in which all wireless communication equipments communicate information and perform control operation on a peer-to-peer basis. The centralization type is one in which the control operation is performed by wireless communication equipment called the base station, and the other wireless communication equipments communicate only with the base station. The "hybrid" is a type of communication in which the control operation is performed by the base station and information is transmitted on a peer-to-peer basis by all of the wireless communication equipment including the base station.
Communication systems include one called the "frequency hopped system" for performing the communication while periodically changing the transmission/receiving frequencies (carrier frequency) as a communication system belonging to the centralization or hybrid type. This type of system requires a base station for applying a timing of frequency hopping, as described in IEEE 802.11 Working Documents, IEEE 802, 11/92-39, "Medium Access Control Protocol for Wireless LANs" (Reference 2), for example.
Also, NIKKEI Communications No.167, Feb. 7, 1994, pp.86-100 (Reference 3) discloses a well known wireless LAN system capable of using a plurality of base stations at the same time, wherein wireless communication equipment under the control of a base station has the function of automatically seeking another base station when the first base station loses the wireless communication capability due to a fault or the like.
A communication system requiring a base station like the centralization or hybrid type described in Reference 1 requires a base station or setting of a wireless communication equipment operating as a base station before the system is configured. A communication system requiring a base station, on the other hand, poses the problem of the system function being incapable of being maintained in the absence of an alternate base station when the base station becomes incapable of communication due to a fault or the like.